Battery module with series connected cells, internal relays and internal battery management system

ABSTRACT

A battery cell monitoring and conditioning circuit is disclosed to facilitate low cost manufacture of battery modules comprising any number of series-connected cells. A battery management system utilizing a plurality of series-connected cell monitoring and conditioning circuits is disclosed. Methods are provided for operating the disclosed circuits.

This application is related to co-pending application HIGH VOLTAGEBATTERY MODULE WITH SERIES CONNECTED CELLS AND INTERNAL RELAYS Ser. No.17/086,865, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

There is a rapidly growing demand for converting a wide variety ofvehicle types to electric propulsion. In order to deliver the bestperformance and efficiency, the electric drivetrains of such vehiclesneed to operate at a direct current (DC) high voltage. Systems operatingat a nominal 400V DC are now common, and higher performance designsusing 800V DC and above are being put into service.

The battery packs to power such systems are increasing in capacity.Packs of over 70 KWh are now common, and some can deliver over 2,000 Aof current. Such levels of power can present many life-threateninghazards both during ordinary assembly and service operations, as well asrescue operations by emergency personnel when electric vehicles areinvolved in a crash or other adverse event.

Exposure to moisture through condensation, precipitation, or accidentalsubmersion can cause a short in the pack and lead to a fire orexplosion.

Large capacity packs typically require a plurality of individual smallcells, groups of which are connected in parallel to achieve desiredcurrent capability, and multiple groups are then connected in series toachieve the desired voltage. Because a large number of cells istypically needed, resulting in substantial weight and bulk, vehiclebattery packs are often constructed of modules. A typical known batterymodule design is a fraction of a pack, sized to facilitate handling, andoften having a module voltage that is considered to be non-hazardous incontact with human skin, below approximately 50V, although somehigher-voltage modules are known.

A new trend in automotive battery design, exemplified by Tesla andothers, is to move away from modular construction and create monolithicbattery packs, comprised directly of cells and meant to benon-serviceable. While this may be practical in mainstream automotiveapplications, in high performance vehicles which see severe use as partof ordinary operation, this approach is undesirable. Such vehiclesexperience regular shock loads and often crash damage. They requirefrequent service, repair and major parts replacement as part of ordinaryuse. A monolithic non-serviceable battery pack runs counter to theserequirements.

In modular packs known in the art, the lower-voltage modules arecommonly connected in series within the pack, to achieve the desiredpack voltage. A pack typically has an enclosure and safety devices suchas relays, fuses, battery management system, current sensing devices,isolation monitoring devices, and the like, contained within theenclosure. Typically, the safety devices are external to the modules andonly one set of safety devices is shared by all the modules in the pack,to reduce cost and manufacturing complexity. These features keep theoverall pack safe as long as it is not opened for service and itsintegrity is not compromised by an accident or other adversecircumstance such as water ingress.

While individual modules known in the art may have a lower voltage thanthe overall pack, they feature groups of cells connected in parallel andtherefore have a large current capability, typically equal to thedesired current capability of the overall pack. This characteristicmakes it impractical to add relays to each module, due to expense ofhigh-current relays and increased resistance that would add up whenmultiple modules are connected in series. As a result, modules known inthe art have external terminals that are always connected to the cellscomprising the module. With large current capability, a short across theexternal terminals can result in very large amount of energy beingreleased and carries a high risk of fire, serious injury, as well aspotential damage to the module.

While not commonly practiced in vehicle battery packs, connecting highvoltage modules in parallel is known in the art. In U.S. Pat. No.10,333,328 to Hom et al., Hom teaches a multi-battery charging station,connecting a plurality of batteries in parallel. Hom teaches a diode orelectrical switch within each battery to manage selective connection ofeach battery to the common power bus for charging. The objective of theinvention taught by Hom is to provide a method of connecting multiplebatteries having different states of charge to a common power bus. Homdoes not contemplate the safe handling of individual batteries, andtherefore does not anticipate isolating both external terminals from thecells within a battery. Hom does not contemplate the internal structureof each battery from a safety perspective. However, the method taught byHom of managing dissimilar states of charge of parallel connectedbatteries is an example of known methods in the art for managing suchconditions.

A further drawback of module or pack construction that utilizes groupsof cells connected in parallel is the fact that if one cell in suchgroup develops an internal short, which is a known failure moderesulting from dendrite growth. The full current of all the other cellsin the group will flow through the failed cell. This can lead to rapidoverheating and a resulting explosion or fire. In order to mitigate thisrisk, individual cells are typically connected to a common bus bar bymeans of fusible links. The fusible links have a resistance that causesheat to be generated as current is increased. Once enough heat isgenerated to melt the link, the connection is broken and the currentinto the failed cell is permanently interrupted. A key drawback of thisapproach is that in ordinary use, the inherent resistance of the fusiblelinks leads to unwanted heat generation and overall energy loss in thepack when operating at high current levels.

Another undesirable effect of a plurality of cells connected in parallelwithin a module is that if one of the cells develops excessiveself-discharge, which is a known defect, then all the cells in parallelwith it will discharge through the defective cell over time. This willreduce the state of charge of the entire group, as a percentage ofmaximum. Because multiple parallel groups are typically connected inseries to form a pack, the overall pack usable capacity at any giventime, as a percentage of maximum, is limited by the state of charge ofthe lowest group. This is due to the fact that energy is removed at thesame rate from all the series connected groups of parallel cells.

Over-discharging the lowest group will lead to permanent damage of thegroup and therefore the entire pack. Discharge must consequently bestopped when lowest allowable state of charge of the lowest group isreached, even though the other groups may still retain higher state ofcharge. In this way, a single defective cell in a pack constructedaccording to methods currently practiced in the art can result ineffectively degrading the capacity of the entire pack. Servicing suchpacks is hazardous and requires specialized training and equipment andis usually not practical.

As commonly practiced in the art, vehicle pack design is an engineeringtradeoff of cost, manufacturing efficiency, and safety. Because cost andmanufacturing efficiency are the highest priorities, safety is mostlyconsidered in the context of a pack when installed in a vehicle and inordinary use. Vehicle battery packs known in the art are extremelyhazardous when opened for service or compromised in a crash or otheradverse event. In those circumstances handling of the packs requireshighly trained personnel and specialized equipment to preventpotentially extensive damage, injury, or even death.

There is a demand to provide electric propulsion for a broad range ofhigh performance vehicles such as off-road, recreational, light marineand light aircraft. Such vehicles see extreme use in ordinary operation,involving frequent crashes and requiring extensive service. Therefore,the designs and priorities employed in construction of mainstreamautomotive battery packs are not practical in such applications.

What is needed in the arts of vehicle batteries is a vehicle batterymodule design that is safe to handle without specialized training orequipment, does not create a hazard when compromised by an adverseevent, allows economical and practical construction of high voltage,high current battery packs, provides for graceful degradation of theassembled pack, allows for easy and economical pack service withoutspecialized training and equipment, and minimizes risk of fire andenergy loss in operation.

In addition to being safe to handle, it is necessary for such a vehiclebattery module to be robust and readily produced with commonly availablematerials and manufacturing techniques.

SUMMARY OF THE INVENTION

A first objective of the present invention is to provide a high voltagebattery module suitable for use in vehicles that is robust in order toendure rough handling in operation, storage and transport.

A second objective of the present invention is to provide a batterymodule design that can be readily and cost effectively constructedutilizing commonly available materials and mass production methods.

To achieve the objectives, a battery module of the present inventioncomprises an enclosure containing a plurality of series-connected cellswhich are electrically isolated from the enclosure. The series-connectedcells may be connected as one continuous string, or as a plurality ofindependent series-connected strings contained within same enclosure.

A first printed circuit board assembly (PCBA) comprising one or morecell monitoring and conditioning circuits is provided. In someembodiments, the first PCBA may also comprise cell interconnect means.In other embodiments the cells may be interconnected by wires. Aplurality of resistors, electrically connected to first PCBA, areprovided to facilitate cell balancing, and also heating of the cellswhen desired. A second PCBA comprising additional cell interconnects maybe utilized in some embodiments.

The portion of the enclosure containing the plurality of seriesconnected cells and the first PCBA may be encapsulated in someembodiments. In such embodiments, the encapsulant used may be of anyknown type including a thermally conductive liquid, a liquid that iscured to a solid, and the like.

An external interface PCBA is provided. In many embodiments the externalinterface PCBA may be separate from the first PCBA and/or the secondPCBA, with electrical and data connections made by means of any knowntype of connector. Other embodiments are possible wherein the externalinterface PCBA is physically integrated with the first and/or secondPCBA.

The external interface PCBA comprises a positive and a negativeelectrical terminal, both said terminals being electrically isolatedfrom said enclosure, and also from said plurality of cells. A firstnormally-open electrical relay is provided to electrically connect thepositive side of the series connected cells to the positive terminal. Asecond normally-open electrical relay is provided to connect thenegative side of the series connected cells to the negative terminal.Many types of relays are known in the art, including electromechanicaland solid state.

In embodiments wherein a plurality of series-connected cell groups iscontained within same enclosure, additional relays may be provided toindividually connect each group of series-connected cells to saidpositive and negative terminals. In such embodiments, additional relaysmay be further provided to connect the separate groups ofseries-connected cells into a continuous group of series-connected cellsby connecting the individual groups in series.

The external interface PCBA further comprises a connection means to anexternal control bus, a battery management system (BMS) circuit, anddata interconnect means for communication between BMS circuit and cellconditioning circuits on the first PCBA.

In many embodiments the external interface PCBA will be a serviceablecomponent, contained in a separate part of the enclosure that is notencapsulated.

A method is disclosed for manufacturing and assembling the module of thepresent invention using know mass-production processes.

A cost-effective cell monitoring and conditioning circuit is disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described herein with reference to thefollowing drawings. The components in the drawings are not necessarilyto scale relative to each other. Like reference numerals designatecorresponding parts throughout the several views.

FIG. 1 is an exploded view of a representative embodiment of the presentinvention utilizing cylindrical cells.

FIG. 2 is an illustration of a representative first PCBA of the presentinvention comprising a plurality of cell interconnects and a pluralityof cell monitoring and conditioning circuits.

FIG. 3 an illustration of a representative second PCBA of the presentinvention.

FIG. 4 shows a plurality of mechanical alignment structures havingresistor retaining means, and a plurality of resistors retained therein.

FIG. 5 shows mechanical alignments structures and retained resistorsassembled to a PCBA

FIG. 6 is a side view of a representative mechanical alignment structurefabricated from stamped aluminum.

FIG. 7 shows a PCBA configured as a flexible circuit and coupled to asingle cylindrical cell.

FIG. 8 is an illustration of cylindrical cells electrically connected inseries and to PCBA by interconnects fabricated from metal wire.

FIG. 9 is a side view of a representative cell interconnect fabricatedfrom stamped copper.

FIG. 10 is an isometric view of a representative cell interconnectfabricated from stamped copper.

FIG. 11 is a partial cross-sectional view of an assembled module of thepresent invention.

FIG. 12 is an illustration of a representative enclosure having a firstcavity and a second cavity.

FIG. 13 shows a representative external interface PCBA configured toconnect two independent groups of series-connected cells individually inparallel or together in series.

FIG. 14 shows a representative external interface PCBA configured toconnect two independent groups of series-connected cells individuallytogether in series.

FIG. 15 is a diagram showing cell monitoring and conditioning circuitsconnected to series-connected cells and resistors.

FIG. 16 illustrates a low cost uplink and downlink circuit forcommunications between cell monitoring and conditioning circuits coupledto series-connected cells.

FIG. 17 is a diagram showing connections between two groups ofseries-connected cells, cell monitoring and conditioning circuits, andexternal interface PCBA.

FIG. 18 is a flow diagram of a method for reporting cell status in asingle cell monitoring and conditioning circuit.

FIG. 19 is a flow diagram of a method for conditioning a cell by asingle cell monitoring and conditioning circuit.

FIG. 20 is a flow diagram of a method for heating a cell by a singlecell monitoring and conditioning circuit.

DETAILED DESCRIPTION

An embodiment of the present invention utilizing cylindrical cells isillustrated in FIG. 1. The illustrated embodiment is not limiting, otherembodiments utilizing different shapes of cells, such as prismatic orpouch type, shall become apparent to those skilled in the art based onthe disclosures made herein.

The disclosed systems and methods for manufacturing a battery module 10will become better understood through review of the following detaileddescription in conjunction with the figures. The detailed descriptionand figures provide examples of the various inventions described herein.Those skilled in the art will understand that the disclosed examples maybe varied, modified, and altered without departing from the scope of theinventions described herein. Many variations are contemplated fordifferent applications and design considerations, however, for the sakeof brevity, each and every contemplated variation is not individuallydescribed in the following detailed description.

Throughout the following detailed description, a variety of examples forsystems and methods for the battery module 10 are provided. Relatedfeatures in the examples may be identical, similar, or dissimilar indifferent examples. For the sake of brevity, related features will notbe redundantly explained in each example. Instead, the use of relatedfeature names will cue the reader that the feature with a relatedfeature name may be similar to the related feature in an exampleexplained previously. Features specific to a given example will bedescribed in that particular example. The reader should understand thata given feature need not be the same or similar to the specificportrayal of a related feature in any given figure or example.

The following definitions apply herein, unless otherwise indicated.

“Substantially” means to be more-or-less conforming to the particulardimension, range, shape, concept, or other aspect modified by the term,such that a feature or component need not conform exactly. For example,a “substantially cylindrical” object means that the object resembles acylinder, but may have one or more deviations from a true cylinder.

“Comprising,” “including,” and “having” (and conjugations thereof) areused interchangeably to mean including but not necessarily limited to,and are open-ended terms not intended to exclude additional, elements ormethod steps not expressly recited.

Terms such as “first”, “second”, and “third” are used to distinguish oridentify various members of a group, or the like, and are not intendedto denote a serial, chronological, or numerical limitation.

“Coupled” means connected, either permanently or releasably, whetherdirectly or indirectly through intervening components.

“Electrically coupled”, “electrically connected” means circuit elementsconnected in a way to enable conduction of electrical current betweenthe elements.

“Connector”, “electrical connector” means a structure or device toelectrically couple circuit elements in a way that is releasable.

“Interconnect”, “electrical interconnect” means a structure or device toelectrically couple circuit elements in a way that is not releasable.

“Communicatively coupled” means that an electronic device is incommunication with another electronic device for the purpose oftransmission of electronic messages, either wirelessly or with aconnector, whether directly or indirectly through a communicationnetwork.

“Controllably coupled” means that an electronic device controlsoperation of another electronic device.

“PCBA” means a printed circuit board assembly, comprising anon-conductive substrate, one or more etched electrically conductivetraces for electrically coupling circuit elements, and one or moreelectrical circuit elements which may be integrated circuits, relays,cell interconnects and the like.

“Resistor” means an electrical circuit element that offers resistance toelectrical current, thereby converting electrical energy into thermalenergy, for the purpose of dissipating said electrical energy, or forthe purpose of heating adjacent components. A resistor may beconstructed from wire, film, coating on a substrate, a transistoroperated in linear region, an array of transistors, or any other knownmeans. Operation of a transistor in linear region creates the effect ofa controlled resistance to current flowing across the transistor and iswell known in the art of transistor design. In some embodiments aresistor may be incorporated into the housing of a battery cell. Inother embodiments a resistor may be incorporated in an integratedcircuit (IC).

“Resistor switch” within the context of the present invention meansspecifically an electrical switch, which may be a transistor, toelectrically connect a resistor in parallel with a single battery cell,so that electrical current may flow from the battery through theresistor, thereby converting a portion of the electrical energy storedin the cell into thermal energy. In some embodiments, resistor switchand resistor may be the same element implemented as a transistoroperated in linear region.

“Mechanical alignment structure” is a system of mechanically retainingand aligning components such as cells, resistors, PCBAs and the like,with respect to each other, during manufacture, assembly and in use. Amechanical alignment structure may have any necessary shape for itsfunction in a specific embodiment and may be fabricated by any availablemeans from any available material, such as metal stamping, plasticinjection molding, and the like.

“Cell”, “battery cell” refers to a single anode and cathode separated byelectrolyte used to produce a voltage and current. A battery module ofthe present invention comprises one or more groups of cells connected inseries within the group. Cells may be cylindrical, prismatic, pouch, orany other type. Cells may be of Lithium-Ion or any other chemical type.

“Communications uplink”, “uplink port”, “uplink” means a digitalcommunications port through which command messages are received andstatus messages are sent.

“Communications downlink”, “downlink port”, “downlink” means a digitalcommunications port through which command messages are sent and statusmessages are received.

“Command message” is an electronic message sent from a first electroniccircuit to a second electronic circuit to initiate an action or statechange by said second circuit.

“Status message” is an electronic message sent by a second electroniccircuit to a first electronic circuit, said message containinginformation pertaining to state or action status of said second circuit,or another circuit.

“Encapsulant” is a fluid that is electrically insulating, but isthermally conductive. Many encapsulants are known. Encapsulants arepoured, injected or drawn into a cavity of a housing, filling voidsbetween components contained therein. In the context of the presentinvention, the primary function of encapsulants is to thermally couplethe encapsulated components to each other and to the housing walls. Someencapsulants are formulated to chemically cure to a solid state afterintroduction into a housing cavity. Such encapsulants serve a secondaryfunction of providing mechanical support to the encapsulated components.Other encapsulants, such as transformer oils, are formulated to remainin a liquid state. Their secondary function is to prevent the entry ofmoisture and contaminants into the encapsulated cavity.

The representative embodiment illustrated as an exploded view in FIG. 1is a battery module comprising 192 cylindrical cells, arranged in twogroups of 96 series-connected cells, each individual group having a netnominal voltage of 400V. The illustrated embodiment is not numericallylimiting, any number of series-connected cell groups may be utilized,with any number of cells in each group, provided that the number ofcells in each group is at least two. Cells may be of cylindrical,prismatic, pouch, or any other type.

The illustrated embodiment of module 10 plurality of cells 400,supported by mechanical alignment structures (MAS) 160 which also retainresistors 420. The MAS 160, cells 400 and resistors 420 are coupled tothe primary PCBA 115, and also secondary PCBA 117. The assembledelements are housed in a first cavity of primary housing 100. Anexternal interface PCBA 925 is housed in a second cavity of housing 100,and is electrically and communicatively coupled to PCBA 115 and PCBA117.

In some embodiments, the first cavity of housing 100 containing thecells 400 will be filled with encapsulant (not shown) that may bethermally conductive, and may be formulated to cure to a solid state.

Thermally conductive endplates 150 are assembled to housing 100, and arethermally coupled to cells 400 by means of encapsulant, while beingelectrically isolated from cells 400.

In some embodiments, the second cavity of housing 100 containing theexternal interface PCBA 925 will be filled with encapsulant that may bethermally conductive, and may be formulated to cure to remain in aliquid state to facilitate servicing or replacement of the PCBA 925while thermally coupling the encapsulated components to the housing, andpreventing entry of moisture and contaminants. Seals of any know typemay be employed as appropriate to prevent loss of liquid encapsulant.

A representative non-limiting embodiment of primary PCBA 115 isillustrated in FIG. 2. It comprises a printed circuit board (PCB) 111, aplurality of cell interconnects 470, a plurality of cell monitoring andconditioning circuits 950, and one communications connector 910 for eachassociated group of series-connected cells that is to be coupled to thePCBA. The PCB 111 comprises a non-conductive substrate on whichelectrical circuits are etched. Such PCBs and circuits are well known,as are means of assembling electrical circuit elements to PCBs, andtherefore the details of their construction are not described orillustrated herein for brevity.

Apertures 175 are illustrated which allow the coupling of cellinterconnects 470 to cells 400 during module manufacture and are notlimiting. Such coupling is most commonly accomplished by welding, thoughother coupling methods may be used. The apertures 175 in the illustratedembodiment only serve the purpose of access for welding, and may not bepresent in embodiments that utilize assembly techniques which do notrequire such access. When apertures 175 are present, they may be of anyappropriate shape and size for the intended function.

Apertures 170 are illustrated for mechanical coupling of mechanicalalignment structures (MAS) to the PCBA 115 and are not limiting. Theillustrated apertures are in the form of oval shaped slots, however anyshape and type of mechanical coupling interface are possible.

An optional secondary PCBA 117 is illustrated in FIG. 3. Its primarypurpose in the illustrated embodiment is to retain and align a pluralityof cell interconnects 470, provide electrical connections between cellinterconnects and resistors 420, and provide electrical connectors 450to connect the groups of cells 400 to external interface PCBA 925. Insome embodiments the cell interconnect and electrical connectors may becoupled directly to the cells, without the need of a dedicated PCBA. Insuch embodiments the secondary PCBA 117 may be omitted.

FIG. 4 illustrates one embodiment of a plurality of mechanical alignmentstructures (MAS) 160 that may be fabricated from stamped aluminum. Thepurpose of MSA 160 within embodiments of the present invention is tomechanically align and couple the various elements of the module 10 withrespect to each other during assembly, and in use. The illustratedembodiment is not limiting in shape, material, or specific function. Aplurality of cylindrical resistors 420 are shown being retained byretaining means 165. Other embodiments utilizing resistors of differentshapes, including those assembled directly to cells, are possible. Insuch embodiments the retaining means 165 may be different or omittedentirely.

Mechanical retention tabs 168 are illustrated which interface withalignment slots 170 of the illustrated PCBA 115 and 117. The illustratedfeatures are only representative and not limiting.

FIG. 5 shows the plurality of MSA 160 and resistors 420 mechanicallycoupled to PCBA 115.

The representative MSA 160 is further illustrated in FIG. 6.

An embodiment having a flexible PCBA 115 mounted directly to cell 400and suitable for series connections to other similarly configuredassemblies is shown in FIG. 7. Interconnect 470 and communications links999 are shown as integral parts of the flexible substrate 111. Resistor420 and battery cell monitoring and conditioning circuit 950 are shownas separate elements, however in some embodiments the resistor 420 maybe incorporated within circuit 950, and may be a transistor or array oftransistors. Circuit 950 is shown having an uplink port 990 and adownlink port 995. Connections between a circuit and interconnectswithin a flexible substrate are well known in the art of PCBAconstruction and are not explicitly shown.

FIG. 8 is a partial illustration of another embodiment of the presentinvention, wherein cells 400 are coupled to PCBA 115 and 117 by means ofconnectors 470 formed from wire, with resistors 420 being soldered toPCBA 115 and 117, and wherein no MSA is present.

FIG. 9 and FIG. 10 illustrate a representative embodiment of cellinterconnect 470 that is formed from copper sheet, and comprisescoupling features 475 for mechanically and electrically coupling theinterconnect to a PCBA. Many types and shapes of cell interconnects, andthe means of coupling them to cells and PCBA, are possible within thescope of the present invention and will be readily apparent to thoseskilled in the art.

FIG. 11 is a partial sectional view of an assembled module 10 thatincludes the thermally conductive endplates 150. A plurality of cells400 are shown housed in a first cavity 110 of housing 100. The cells areelectrically and mechanically coupled to PCBAs 115 and 117 by cellinterconnects 470. External Interface PCBA 925 is shown contained in asecond cavity 120 of housing 100, electrically coupled to PCBA 117 byconnectors 450 and communicatively coupled to PCBA 115 by connectors910. PCBA 115 is shown further comprising battery cell monitoring andconditioning circuits 950.

Partition wall 125 of housing 100, further illustrated in FIG. 12,separates cavities 110 and 120 in the illustrated embodiment, for thepurpose of encapsulating cavity 110 with a first type of encapsulant,and in some embodiments encapsulating cavity 120 with a second type ofencapsulant. Partition wall 125 is illustrative and not limiting. Whenpartition wall 125 is present, apertures may exist in the wall forpassing of connectors 450 and 910, as appropriate to the specificembodiment. In some embodiments the partition wall 125 may be formed asthe surface of a volume of encapsulant that is poured to partially fillan enclosure and subsequently cured to a solid state. In otherembodiments, a portion or the entirety of one or more exterior walls ofthe enclosure 100 may be formed as a surface of a volume of encapsulantthat has been cured to a solid state.

Also illustrated in FIG. 11 is a negative terminal 300, being accessiblevia negative terminal aperture 305 of housing 100. The cross sectionalview does not show positive terminal 200 or control bus connector 700.The illustration further shows a representative location of relay 600assembled to PCBA 925.

A representative housing 100 is further illustrated in FIG. 12, showinga first cavity 110, a second cavity 120, a partition wall 125, apositive terminal aperture 205, a control bus connector aperture 705,and a negative terminal aperture 305. The shapes, location and functionof the illustrated apertures are not limiting. In some embodiments, allsuch functions may be combined into a single aperture. Other embodimentsmay place apertures on different faces of the enclosure, and may combinethem with mechanical retention and other functions. Seals and safetyfeatures of any known type may be employed without departing from thescope of the invention.

One embodiment of an external interface PCBA 925 is shown in FIG. 13,comprising positive terminal 200, negative terminal 300, batterymanagement system (BMS) circuit 900, control bus connector 700,connectors 450 for electrically coupling to groups of series-connectedcells 400, and communication connectors 910 (see also FIG. 11) forcommunicatively coupling to PCBA 115 and the cell monitoring andconditioning circuits 950 (see also FIG. 11) comprised therein. Acurrent sensor 905 is illustrated as being coupled to the positiveterminal 200, other embodiments may couple a current sensor to negativeterminal 300. A voltage measurement circuit 907 is shown connected toterminals 200 and 300. In some embodiments, voltage measurement circuit907 may be internal to BMS circuit 900. Relays 500, 550, 600, 650 and660 are also shown. The relays 500, 550, 600, 650 and 660 function inconjunction with PCBA 115 and two groups of series connected cells 400is further diagrammatically illustrated in FIG. 17.

In some embodiments, relays 500 and 550 may be of a first type, andrelays 600 and 650 may be of a second type. For example if the firsttype of relay is electromechanical it provides complete galvanicisolation when open. However, electromechanical relays are relativelyslow to respond. If the second type of relay is solid state, whichrespond to control input very quickly, they can be used to open thecircuit if current sensor 905 detects excessive current. Some solidstate relays may not provide complete galvanic isolation. By utilizingtwo distinct types of relays, a PCBA 925 can provide both full galvanicisolation and fast response to excessive current conditions.

In some embodiments, the current sensor 905 may be of Hall Effect type.

Another embodiment of PCBA 925 is shown in FIG. 14 wherein relays 550,650 and 660 are omitted, and relay 660 is instead replaced byinterconnect 665 to connect two groups of series-connected cells 400 inseries with each other, thereby forming a single group ofseries-connected cells.

In some embodiments, interchangeable configurations of PCBA 925 may beprovided to configure the groups of series connected cells within amodule by connecting them in parallel or in series, as desired. Thisinterchangeability allows a module to be configured for operation atdifferent voltages, for example 400V and 800V, after the module has beenassembled, and the cavity 110 containing the cells 400 has beenencapsulated with an encapsulant formulated to cure to a solid state.

In some embodiments, the functionality of PCBA 925 may be physicallycombined with functionality of PCBA 115 in a single assembly, withoutdeparting from the scope of the present invention.

In other embodiments, PCBA 115 may be comprised of a plurality ofsubstantially identical assemblies electrically and communicativelycoupled in series.

FIG. 15 is a diagrammatic illustration of the PCBA 115 with cellmonitoring and conditioning circuits 950 of the present invention, andtheir connections to other elements of a module of the presentinvention. Elements shown in FIG. 15 without reference numerals are thesame as like elements identified by reference numerals.

The illustrated configuration connects one circuit 950 to two among agroup of series connected cells 400 by means of interconnects 940, whichmay be PCB traces. The cells are electrically connected in series withinthe module by interconnects 470. A single resistor 420 is shared betweenthe two corresponding cells 400, and is alternatingly connected inparallel with one and then the other of the two cells by resistorswitches 980, under the control of controller 955.

The illustrated circuit 950 further comprises a voltage measurementcircuit 960 for each connected cell, a temperature measuring circuit965, an uplink digital port 990 and a downlink digital port 995. Theuplink port 990 of each circuit 950 is communicatively connected to thedownlink port 995 of an adjacent circuit 950 by means of digital link999 that is coupled to communication connector 910, with the exceptionsthat the uplink port of the first circuit 950 in the chain iscommunicatively connected to BMS circuit 900 on PCBA 925 by means ofconnector 910, and the downlink port of the last circuit 950 in thechain is not connected.

The positive power supply rail 970 of circuit 950 of the presentinvention is connected to the positive terminal of the most positiveamong the connected cells 400, and the negative power supply rail 975 ofcircuit 950 is connected to the negative terminal of the most negativeamong the connected cells 400.

A key distinguishing feature of the circuit 950 of the present inventionis the separate and distinct uplink port 990 and downlink port 995.Ports for message communication are well known in the art. However thecommon approach is to connect such ports to a communications bus, suchas CAN bus, I2C bus, or the like. In a battery module having a pluralityof series-connected cells, and a management circuit coupled to eachcell, a very large voltage potential difference would exist betweencircuit connected to most positive cell, and one connected to mostnegative cell.

If the circuits are connected to a common message bus, thecommunications ports would have to be capable of accepting signals fromother circuits at a very large voltage difference. While solutions foraccommodating large voltage differences exist in the art, such asoptical isolation, they significantly increase the cost and thereforerun counter to the objectives of the present invention.

By specifying that uplink port 990 and downlink port 995 for eachcircuit 950 are distinct and separate, the communications links 999 aretherefore implemented as point-to-point links rather than a bus. Thisrequires that only the voltage differences between two adjacent circuits950 be accommodated, which are small and can be readily implemented withinexpensive circuit components.

Some aspects of the illustrated configuration are advantageous but notlimiting. Configurations of circuit 950 having connections only for asingle cell and corresponding resistor, or more than twoseries-connected cells and corresponding resistors, shall be readilyapparent to those skilled in the art. The illustrated configurationprovides the advantage of keeping the working voltages within eachcircuit low, reducing voltage potential between adjacent circuits, andsimplifying PCB trace routing.

In particular, since uplink and downlink ports must be tolerant of inputvoltages above the local positive supply rail 970, and below the localnegative supply rail 975, keeping the working voltages low allows theuse of lower cost circuits to implement the links.

FIG. 16 illustrates one embodiment of a low cost communications link 999as a two-wire serial link. Like elements in FIG. 15 and FIG. 16 are notdescribed hereinbelow for brevity. Signaling between adjacent circuits950 is achieved by utilizing n-FET switch 991 with a pulldown resistor993 on the uplink digital port 990 and a p-FET switch 992 with pullupresistor 994 on the downlink digital port 995. The illustratedembodiment allows for accommodating the voltage differences betweenadjacent circuits 950. The illustrated configuration allows the uplinkdigital ports 990 to accept signals which have a voltage that is abovethe voltage of positive power supply rail 970, and allows the downlinkdigital ports 995 to accept signals that may have a voltage that isbelow the voltage of the negative power supply rail 975. Many otherembodiments are possible utilizing other circuit components with similarfunctionality.

The illustrated configuration further allows the circuit to be poweredand continue to function in the event one of the connected cellsdevelops an internal short and consequently presents reduced or zerovoltage across its terminals.

These advantages serve the primary objective of enabling the manufactureof a reliable and safe module using readily available low cost massproduction methods and materials.

Another embodiment is illustrated in FIG. 17 showing a cell monitoringand conditioning circuit 950 configured to be coupled to a single cell.Like elements in FIG. 15, FIG. 16, and FIG. 17 are not describedhereinbelow for brevity. In this embodiment, the resistor 420 is coupledto PCBA 115 together with circuit 950. The illustrated embodiment showsresistor 420 as a separate element for clarity, however in otherembodiments resistor 420 may be incorporated internally in circuit 950as a transistor or an array of transistors operated in linear region,which may also act as resistor switch.

A separate dedicated PCBA 115 comprising a circuit 950 and a resistor420 is mechanically thermally and electrically coupled to eachcorresponding cell in a module 10. The cells are electrically connectedin series within the module by interconnects 470, and individual PCBAs115 are correspondingly communicatively connected in series bycommunications links 999. In such embodiments PCBA 115 may beconstructed as a flexible circuit.

Circuit 950 is preferably implemented as an application specificintegrated circuit (ASIC) for the purpose of cost reduction. Embodimentsutilizing discrete commercially available components can readily bebuilt and shall become apparent to those skilled in the art ofelectrical circuit design based on disclosures made herein.

Some of the unique and distinguishing characteristics of the circuit 950of the present invention are the uplink port 990 and downlink port 995for connecting adjacent identical circuits in a chain to accommodate anynumber of series-connected cells, and facilitating the control of theentire chain of circuits 950 from a single BMS circuit 900. The uniquemethods for operating such circuits are further disclosed herein.

Another unique feature of the illustrated circuit 950 is the ability toshare one resistor between two cells, reducing overall component count,complexity and cost. This functionality is not limited to the two-cellconfiguration and may be readily implemented in a circuit configured toconnect to any even number of series-connected cells.

Another unique characteristic of the present invention is the ability toheat the cells 400 by dissipating some of the electrical energy storedin the cell in the resistor 420 when maintaining cells at a temperatureabove ambient is desired.

A conceptual representation of full electrical functionality of thecircuits disclosed herein is shown in FIG. 17. The illustration is of aconfiguration having two groups of four series-connected cells forclarity. It shall be readily apparent to one skilled in the art howconfigurations having any number of groups or any number ofseries-connected cells may be constructed based on the disclosures madeherein.

The diagram of FIG. 17 shows a PCBA 115 comprising four circuits 950,two for each of the two groups of 4 series-connected cells. A singleresistor 420 is shared between each pair of series-connected cells thatare coupled to a single circuit 950 by interconnects 940. Interconnects940 may be printed circuit traces, wires, integrated circuit packagepins, or any combination thereof. Cells are connected in series by cellinterconnects 470. Electrical connectors 450 and communicationconnectors 910 between PCBA 115 and PCBA 925 are diagrammaticallyrepresented.

In some embodiments, connectors 910 will feature galvanic isolation bymeans of optical, inductive or wireless coupling. PCBA 115 and PCBA 925are illustrated as separate for clarity of function, however they may becombined into a single physical assembly in some embodiments. In otherembodiments PCBA 115 may comprise a plurality of substantially identicalassemblies.

The illustrated configuration of PCBA 925 facilitates the connection ofthe two groups of series-connected cells in parallel with each other, orin series with each other, by means of relays under the control of theBMS circuit 900. For series configuration, relays 500, 600, and 660 areclosed while relays 550 and 650 are open. To achieve parallel connectionof the groups, relays 500, 550, 600 and 650 are closed while relay 660is open. For safety when not in use, full isolation of terminals 200 and300 is achieved by opening all the relays.

The illustrated BMS circuit 900 comprises two downlink ports 995, eachbeing communicatively connected via communications link 999 andcommunications connector 910 to a chain of circuits 950, each chaincorresponding to a group of series-connected cells 400.

A control bus port 700 is provided for communication with an externalcontroller such as pack controller, vehicle controller (VCU), chargerand the like.

In some embodiments, terminals 200 and 300, and control bus port 700,may be combined into a single physical connector.

Additional low voltage power connector may be provided in someembodiments to power the BMS circuit 900 and relays 500, 550, 600, 650and 660 independently of the cells 400.

Methods for operation of a circuit 950 of the present invention areconceptually represented in FIG. 18, FIG. 19 and FIG. 20. The methodsare described with regard to a single cell coupled to a circuit 950. Inconfigurations where more than one of a series-connected cells arecoupled to a single circuit 950, the method is repeated for each coupledcell. Such repetition shall be readily apparent to those skilled in theart and therefore the detailed description thereof is omitted forbrevity.

To obtain the status, which may include cell voltages and temperatures,of the entire module, the BMS circuit 900 issues a status requestcommand message via downlink 995 to a first circuit 950 coupled tocircuit 900 by means of a communications link 999 and the communicationsconnector 910.

As illustrated in FIG. 18, upon receipt of the status request commandmessage via its uplink 990 in step A, each circuit 950 reissues samestatus request command message on its downlink 995 to the next circuit950 in the series-connected chain in step B.

The circuit 950 then measures the status of its coupled cell in step C,then transmits the results via its uplink in step D.

If more than one series connected cell is coupled to a circuit 950,steps C and D are repeated for each cell. This repetition is notexplicitly illustrated in FIG. 18.

In steps E and F the circuit 950 then waits to receive status messagesfrom subsequent circuits 950 in the chain. For each such messagereceived, step D is repeated transmitting via uplink the status messagereceived via downlink.

In some embodiments, a predetermined period of inactivity may bespecified after which circuit 950 enters a low power mode. When in lowpower mode, a circuit 950 may be configured to wake on receipt of amessage, such as at step A.

Once all the status request command messages are transmitted viadownlinks to all circuits 950 in the chain, and resulting statusmessages are transmitted via uplinks back to circuit 900, the circuit900 will have received the status of all the cells in the module.

To balance all the cells in the module, the BMS circuit 900 will firstcompare all cell voltages reported in response to status request commandmessage, select a suitable target voltage, which may be the lowest amongreported voltages, or another value arrived at by an algorithm.

Circuit 900 then issues a target cell voltage command message viadownlink 995 to a first circuit 950 coupled to circuit 900 by means of acommunications link 999 and the communications connector 910.

As illustrated in FIG. 19, upon receipt of the target cell voltagecommand message via its uplink 990 in step H, each circuit 950 reissuessame target cell voltage command message on its downlink 995 to the nextcircuit 950 in the series-connected chain in step J.

The circuit 950 then measures the voltage of its coupled cell in step K.If the measured cell voltage is above the commanded target cell voltagebased on comparison made in step L, circuit 950 will connect the coupledresistor 420 in parallel with the coupled cell by means of resistorswitch 980 for a predetermined amount of time in step M. Upon expirationof the predetermined amount of time the resistor is decoupled from thecell in step N. In some embodiments the resistor 420 and resistor switch980 may be one in the same, implemented as a transistor or an array oftransistors, operated in linear region. In some embodiments thisresistance may be varied to produce a desired rate of energy dissipationin the resistor.

If more than one series connected cell is coupled to a circuit 950,steps K through N are repeated for each cell. This repetition is notexplicitly illustrated in FIG. 19.

To maintain all the cells in the module at a predetermined temperature,the BMS circuit 900 issues a target cell temperature command message viadownlink 995 to a first circuit 950 coupled to circuit 900 by means of acommunications link 999 and the communications connector 910.

As illustrated in FIG. 20, upon receipt of the target cell temperaturecommand message via its uplink 990 in step Q, each circuit 950 reissuessame target cell temperature command message on its downlink 995 to thenext circuit 950 in the series-connected chain in step R.

The circuit 950 then measures the temperature of its coupled cell instep S. In some embodiments, the circuit 950 may be thermally coupled toa plurality of cells, or may be configured to measure the localtemperature in proximity of one or more cells rather than that of anyone cell directly. For the purposes of this description and the claimsbased thereon, all such measurements are considered cell temperaturemeasurements.

If the measured cell or local temperature is below the commanded targetcell temperature based on comparison made in step T, circuit 950 willconnect the coupled resistor 420 in parallel with the coupled cell bymeans of resistor switch 980 for a predetermined amount of time in stepU. Upon expiration of the predetermined amount of time the resistor isdecoupled from the cell in step V. In some embodiments the resistor 420and resistor switch 980 may be one in the same, implemented as atransistor or an array of transistors, operated in linear region. Insome embodiments this resistance may be varied to produce a desired rateof energy dissipation in the resistor.

The embodiments disclosed herein are illustrative and not limiting;other embodiments shall be readily apparent to those skilled in the artbased upon the disclosures made herein, without departing from the scopeof the present invention.

It should be emphasized that the above-described embodiments of thebattery module 10 are merely possible examples of implementations of theinvention. Many variations and modifications may be made to theabove-described embodiments. All such modifications and variations areintended to be included herein within the scope of this disclosure andprotected by the following claims.

Furthermore, the disclosure above encompasses multiple distinctinventions with independent utility. While each of these inventions hasbeen disclosed in a particular form, the specific embodiments disclosedand illustrated above are not to be considered in a limiting sense asnumerous variations are possible. The subject matter of the inventionsincludes all novel and non-obvious combinations and sub combinations ofthe various elements, features, functions and/or properties disclosedabove and inherent to those skilled in the art pertaining to suchinventions. Where the disclosure or subsequently filed claims recite “a”element, “a first” element, or any such equivalent term, the disclosureor claims should be understood to incorporate one or more such elements,neither requiring nor excluding two or more such elements.

Applicant(s) reserves the right to submit claims directed tocombinations and sub combinations of the disclosed inventions that arebelieved to be novel and non-obvious. Inventions embodied in othercombinations and sub combinations of features, functions, elementsand/or properties may be claimed through amendment of those claims orpresentation of new claims in the present application or in a relatedapplication. Such amended or new claims, whether they are directed tothe same invention or a different invention and whether they aredifferent, broader, narrower, or equal in scope to the original claims,are to be considered within the subject matter of the inventionsdescribed herein.

Therefore, having thus described the invention, at least the followingis claimed:
 1. A battery cell monitoring and conditioning circuit thatmonitors at least a battery cell, said circuit comprising: a controller;an uplink port for receiving command messages and transmitting statusmessages by the controller; a downlink port for transmitting commandmessages and receiving status messages by the controller, said downlinkport being distinct and separate from said uplink port; a voltagemeasurement circuit communicatively coupled to said controller thatmeasures at least a voltage of at least the battery cell; a firstinterconnect to connect to a positive terminal of at least the batterycell; a second interconnect to connect to a negative terminal of atleast the battery cell; and a resistor switch controllably coupled tothe controller, where the resistor switch is capable of electricallycoupling a resistor to one of said negative battery cell terminal of atleast the battery cell and said positive battery cell terminal of atleast the battery cell, wherein a positive power supply rail of saidcircuit is electrically coupled to said first interconnect to connect tosaid positive terminal of at least the battery cell, and a negativepower supply rail of said circuit is electrically coupled to said secondinterconnect to connect to said negative terminal of said at least thebattery cell, and wherein said uplink port is configured to acceptsignals at a first voltage above said positive power supply railvoltage, and said downlink port is configured to accept signals at asecond voltage below said negative power supply rail voltage.
 2. Thecircuit of claim 1 wherein said resistor is integrated into saidcircuit.
 3. The circuit of claim 1 wherein said resistor and saidresistor switch is a transistor operated in a linear region.
 4. Thecircuit of claim 1 further comprising a temperature measuring circuitconfigured to measure a temperature in proximity to said at least thebattery cell.